The Gaslow Auto Changeover Head is designed to screw on to a 30mbar caravan/motorhome regulator.We stock a wide range of hoses to suit many cylinders - all of which are compatible with this unit.Select which cylinder you would like to use first by rotating the indicator to the right or leftTurn on both cylinders and the display will go green to show the primary cylinder is in use.When gas levels run low, the sensing device automatically changes to the reserve cylinder without interrupting the flow of gas.The display will now show red to indicate the primary cylinder is empty and the reserve cylinder is in use.The built-in non return valve allows disconnection of the empty cylinder without disrupting the supply.